Organometallic compounds having sterically hindered amides

ABSTRACT

This invention relates to organometallic compounds represented by the formula M(NR 1 R 2 ) x  wherein M is a metal or metalloid, R 1  is the same or different and is a hydrocarbon group or a heteroatom-containing group, R 2  is the same or different and is a hydrocarbon group or a heteroatom-containing group; R 1  and R 2  can be combined to form a substituted or unsubstituted, saturated or unsaturated cyclic group; R 1  or R 2  of one (NR 1 R 2 ) group can be combined with R 1  or R 2  of another (NR 1 R 2 ) group to form a substituted or unsubstituted, saturated or unsaturated cyclic group; x is equal to the oxidation state of M; and wherein said organometallic compound has (i) a steric bulk sufficient to maintain a monomeric structure and a coordination number equal to the oxidation state of M with respect to anionic ligands, and (ii) a molecular weight sufficient to possess a volatility suitable for vapor deposition; a process for producing the organometallic compounds, and a method for producing a film or coating from organometallic precursor compounds.

RELATED APPLICATION

This application is a divisional application of prior U.S. applicationSer. No. 11/807,142, filed May 25, 2007, now allowed, which claimspriority to U.S. Provisional Application Ser. No. 60/818,506, filed onJul. 6, 2006, the entire contents of which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

This invention relates to organometallic compounds containing stericallyhindered amides, a process for producing the organometallic compoundscontaining sterically hindered amides, and a method for producing a filmor coating from organometallic precursor compounds containing stericallyhindered amides.

BACKGROUND OF THE INVENTION

Chemical vapor deposition methods are employed to form films of materialon substrates such as wafers or other surfaces during the manufacture orprocessing of semiconductors. In chemical vapor deposition, a chemicalvapor deposition precursor, also known as a chemical vapor depositionchemical compound, is decomposed thermally, chemically, photochemicallyor by plasma activation, to form a thin film having a desiredcomposition. For instance, a vapor phase chemical vapor depositionprecursor can be contacted with a substrate that is heated to atemperature higher than the decomposition temperature of the precursor,to form a metal or metal oxide film on the substrate. Preferably,chemical vapor deposition precursors are volatile, heat decomposable andcapable of producing uniform films under chemical vapor depositionconditions.

The semiconductor industry is currently considering the use of thinfilms of various metals for a variety of applications. Manyorganometallic complexes have been evaluated as potential precursors forthe formation of these thin films. A need exists in the industry fordeveloping new compounds and for exploring their potential as chemicalvapor deposition precursors for film depositions.

Lanthanide-based materials such as oxides, silicates, aluminates, andsilicon/aluminum oxynitrides are candidates for high-K dielectrics innext-generation semiconductor devices. However, due to the inherentproperties of the lanthanides, such as larger atomic radii (compared totransition metals), participation of the f-orbitals, and propensity forthe +3 oxidation state (Cotton, F. A.; Wilkenson, G. W. AdvancedInorganic Chemistry; Schumann et al., Chem. Rev. 2002, 102, 1851)lanthanide systems often have high-coordination numbers and form dimers,higher oligomers, and/or adducts with other molecules. This scenario isthe case for many amide-based systems, and severely limits theavailability of stable compounds with sufficient volatility for chemicalvapor deposition and atomic layer deposition applications.

U.S. Patent Application Publication Nos. US 2002/0187644 A1 and US2002/0175393 A1 disclose metalloamide precursor compositions havingstated utility for forming dielectric thin films such as gatedielectric, high dielectric constant metal oxides, and ferroelectricmetal oxides and to a low temperature chemical vapor deposition processfor deposition of such dielectric thin films utilizing the compositions.

In developing methods for forming thin films by chemical vapordeposition or atomic layer deposition methods, a need continues to existfor precursors that preferably are liquid at room temperature, haveadequate vapor pressure, have appropriate thermal stability (i.e., forchemical vapor deposition will decompose on the heated substrate but notduring delivery, and for atomic layer deposition will not decomposethermally but will react when exposed to co-reactant), can form uniformfilms, and will leave behind very little, if any, undesired impurities(e.g., halides, carbon, etc.). Therefore, a need continues to exist fordeveloping new compounds and for exploring their potential as chemicalvapor or atomic layer deposition precursors for film depositions. Itwould therefore be desirable in the art to provide a precursor thatpossesses some, or preferably all, of the above characteristics.

SUMMARY OF THE INVENTION

This invention relates in part to organometallic compounds representedby the formula M(NR₁R₂)_(x) wherein M is a metal or metalloid, R₁ is thesame or different and is a hydrocarbon group or a heteroatom-containinggroup, R₂ is the same or different and is a hydrocarbon group or aheteroatom-containing group; R₁ and R₂ can be combined to form asubstituted or unsubstituted, saturated or unsaturated cyclic group; R₁or R₂ of one (NR₁R₂) group can be combined with R₁ or R₂ of another(NR₁R₂) group to form a substituted or unsubstituted, saturated orunsaturated cyclic group; x is equal to the oxidation state of M; andwherein said organometallic compound has (i) a steric bulk sufficient tomaintain a monomeric structure and a coordination number equal to theoxidation state of M with respect to anionic ligands, and (ii) amolecular weight sufficient to possess a volatility suitable for vapordeposition.

This invention also relates in part to a process for the production ofan organometallic compound comprising (i) reacting in a first pot anitrogen-containing compound with an alkali metal, or an alkalimetal-containing compound, or an alkaline earth metal, or an alkalineearth metal-containing compound, in the presence of a solvent and underreaction conditions sufficient to produce a first reaction mixturecomprising a base material, (ii) adding said base material to a secondpot containing a metal source compound and optionally an amine compound,(iii) reacting in said second pot said base material with said metalsource compound and optionally said amine compound under reactionconditions sufficient to produce a second reaction mixture comprisingsaid organometallic compound, and (iv) separating said organometalliccompound from said second reaction mixture; wherein said organometalliccompound is represented by the formula M(NR₁R₂)_(x) wherein M is a metalor metalloid, R₁ is the same or different and is a hydrocarbon group ora heteroatom-containing group, R₂ is the same or different and is ahydrocarbon group or a heteroatom-containing group; R₁ and R₂ can becombined to form a substituted or unsubstituted, saturated orunsaturated cyclic group; R₁ or R₂ of one (NR₁R₂) group can be combinedwith R₁ or R₂ of another (NR₁R₂) group to form a substituted orunsubstituted, saturated or unsaturated cyclic group; x is equal to theoxidation state of M; and wherein said organometallic compound has (i) asteric bulk sufficient to maintain a monomeric structure and acoordination number equal to the oxidation state of M with respect toanionic ligands, and (ii) a molecular weight sufficient to possess avolatility suitable for vapor deposition. The organometallic compoundyield resulting from the process of this invention can be 60% orgreater, preferably 75% or greater, and more preferably 90% or greater.

This invention further relates in part to a method for producing a film,coating or powder by decomposing an organometallic precursor compoundrepresented by the formula M(NR₁R₂)_(x) wherein M is a metal ormetalloid, R₁ is the same or different and is a hydrocarbon group or aheteroatom-containing group, R₂ is the same or different and is ahydrocarbon group or a heteroatom-containing group; R₁ and R₂ can becombined to form a substituted or unsubstituted, saturated orunsaturated cyclic group; R₁ or R₂ of one (NR₁R₂) group can be combinedwith R₁ or R₂ of another (NR₁R₂) group to form a substituted orunsubstituted, saturated or unsaturated cyclic group; x is equal to theoxidation state of M; and wherein said organometallic compound has (i) asteric bulk sufficient to maintain a monomeric structure and acoordination number equal to the oxidation state of M with respect toanionic ligands, and (ii) a molecular weight sufficient to possess avolatility suitable for vapor deposition; thereby producing the film,coating or powder. Typically, the decomposing of said organometallicprecursor compound is thermal, chemical, photochemical orplasma-activated.

This invention yet further relates in part to organometallic precursorcompound mixtures comprising (a) an organometallic precursor compoundrepresented by the formula M(NR₁R₂)_(x) wherein M is a metal ormetalloid, R₁ is the same or different and is a hydrocarbon group or aheteroatom-containing group, R₂ is the same or different and is ahydrocarbon group or a heteroatom-containing group; R₁ and R₂ can becombined to form a substituted or unsubstituted, saturated orunsaturated cyclic group; R₁ or R₂ of one (NR₁R₂) group can be combinedwith R₁ or R₂ of another (NR₁R₂) group to form a substituted orunsubstituted, saturated or unsaturated cyclic group; x is equal to theoxidation state of M; and wherein said organometallic compound has (i) asteric bulk sufficient to maintain a monomeric structure and acoordination number equal to the oxidation state of M with respect toanionic ligands, and (ii) a molecular weight sufficient to possess avolatility suitable for vapor deposition; and (b) one or more differentorganometallic precursor compounds (e.g., a hafnium-containing,aluminum-containing, strontium-containing, barium-containing,titanium-containing organometallic precursor compound).

This invention relates in particular to ‘next generation’ depositionsinvolving amide-based lanthanide precursors. These precursors can haveadvantages over the other known precursors. These lanthanum-containingmaterials can be used for a variety of purposes such as dielectrics,barriers, and electrodes, and in many cases show improved properties(thermal stability, desired morphology, less diffusion, lower leakage,less charge trapping, and the like) than other metal containing films.

The invention has several advantages. For example, the processes of theinvention are useful in generating organometallic compounds that havevaried chemical structures and physical properties. Films generated fromthe organometallic compound precursors can be deposited with a shortincubation time, and the films deposited from the organometalliccompound precursors exhibit good smoothness.

This invention relates in particular to chemical vapor deposition andatomic layer deposition precursors for next generation devices,specifically organometallic precursors are preferred that are liquid atroom temperature, i.e., 20° C.

The organometallic precursor compounds of this invention can providedesired properties of an atomic layer deposition precursor forapplications involving nanolaminate structures in tandem with othermaterials, for example, a material such as Al₂O₃.

DETAILED DESCRIPTION OF THE INVENTION

As indicated above, this invention relates to organometallic compoundsrepresented by the formula M(NR₁R₂)_(x) wherein M is a metal ormetalloid, R₁ is the same or different and is a hydrocarbon group or aheteroatom-containing group, R₂ is the same or different and is ahydrocarbon group or a heteroatom-containing group; R₁ and R₂ can becombined to form a substituted or unsubstituted, saturated orunsaturated cyclic group; R₁ or R₂ of one (NR₁R₂) group can be combinedwith R₁ or R₂ of another (NR₁R₂) group to form a substituted orunsubstituted, saturated or unsaturated cyclic group; x is equal to theoxidation state of M; and wherein said organometallic compound has (i) asteric bulk sufficient to maintain a monomeric structure and acoordination number equal to the oxidation state of M with respect toanionic ligands, and (ii) a molecular weight sufficient to possess avolatility suitable for vapor deposition. The organometallic compoundsof this invention are preferably a liquid at 20° C.

Maintaining the monomeric nature of the organometallic molecules isimportant to achieve sufficient volatility. The formation of dimers,oligomers, or other species containing two or more metal centers mayrender the compound too large, and thus the additional molecular weightcan limit utilization as a precursor.

The steric bulk of the organometallic molecule, as imparted by the bulkyamide ligands, is important to prevent the formation of dimers,oligomers, or other species containing two or more metal centers, whichcan limit volatility. Furthermore, the steric bulk inhibits coordinationnumbers higher than the oxidation state of the central element, whichaids in the prevention of the formation of less volatile and more polarspecies (e.g., the so called ‘ate’ compounds, which can incorporatealkali metals (e.g., Li) and halogens (e.g., Cl) if present during thereaction). It should be noted that in some cases coordination of a smallneutral molecule (e.g., diethyl ether, trimethylamine), althoughtechnically increasing the coordination number above the oxidation stateof the central element, may yield a precursor with acceptableproperties, and is within the scope of this invention.

The organometallic compounds of this invention preferably have a stericbulk greater than the steric bulk of tris(diethylamino)lanthanum ortris(diisopropylamino)lanthanum.

The molecular weight of the organometallic molecules is limited by therequirement for sufficient volatility. Although a molecule may bemonomeric with a coordination number equivalent to the oxidation stateof the central element, if the ligands are too large (e.g., highmolecular weight), the compound may not be useful as a precursor due tolack of vapor pressure. The organometallic molecules of this inventionare preferably neutral molecules that are not dimers, oligomers, orother species containing two or more metal centers.

Typically, the organometallic compounds of this invention have amolecular weight of less than about 1000, preferably less than about750, and more preferably less than about 500.

The organometallic compounds of this invention have a melting pointsufficient for vapor deposition. Typically, the organometallic compoundshave a melting point less than about 200° C., preferably less than about100° C., and more preferably less than about 50° C.

The organometallic compounds of this invention have a volatilitysuitable for vapor deposition. Typically, the organometallic compoundsof this invention have a volatility of at least 0.1 Torr at 200° C.,preferably a volatility of at least 0.1 Torr at 150° C., and morepreferably a volatility of at least 0.1 Torr at 100° C.

The organometallic compounds of this invention exhibit thermal stabilitysufficient for vapor deposition. Typically, the organometallic compoundshave a thermal stability in which less than about 1 weight percent ofsaid organometallic compound decomposes at a temperature of 100° C. overa period of 1 day, preferably a thermal stability in which less thanabout 1 weight percent of said organometallic compound decomposes at atemperature of 100° C. over a period of 1 month, and more preferably athermal stability in which less than about 1 weight percent of saidorganometallic compound decomposes at a temperature of 100° C. over aperiod of 1 year.

Typically, R₁ and R₂ are the same or different and are independentlyhydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl,tert-butyl, tert-amyl, cyclohexadienyl, adamantyl, phenyl, benzyl,silyl, dimethylsilyl, diethylsilyl, trimethylsilyl, triethylsilyl,dimethylethylsilyl, diethylmethylsilyl, and the like.

In general, R₁ and R₂ are the same or different and are independentlyhydrogen, alkyl; a substituted or unsubstituted, saturated orunsaturated, hydrocarbon, aromatic hydrocarbon, cycloaliphatichydrocarbon, aromatic heterocycle, cycloaliphatic heterocycle, alkylhalide, silylated hydrocarbon, ether, polyether, thioether, ester,lactone, amide, amine, polyamine, nitrile; or mixtures thereof. R₁ andR₂ can also include substituted or unsubstituted, saturated orunsaturated, cyclic amido or amino groups, for example, aziridinyl,azetidinyl, pyrrolidinyl, thiazolidinyl, piperidinyl, pyrrolyl,pyridinyl, pyrimidinyl, pyrrolinyl, pyrazolyl, thiazolyl, oxazolyl,imidazolyl, imidazolidinonyl, imidazolidinethionyl, quinolinyl,isoquinolinyl, carbazolyl, triazolyl, indolyl and purinyl. Preferably,each of R₁ and R₂ is the same or different and is independentlyhydrogen, alkyl, or mixtures thereof.

Typically, M is a Group 2 (e.g., Sr, Ba) Group 3 (e.g., Sc, Y), Group 13(Al, Ga) or a lanthanide series element (e.g., La, Ce, Pr, Nd, Dy, Er,and Yb). M can also be a Group 1, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15,16, 17, 18 or an actinide series element. M is preferably selected froma Group 2 element, a Group 13 element, a Group 14 element, a transitionmetal, or a lanthanide series element. More preferably, M is selectedfrom Sr, Ba, Sc, Y, Al, Ga, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er,Tm, Yb, and Lu.

Illustrative organometallic compounds of this invention include, forexample, tris(bis(cyclohexyl)amino)lanthanum,tris(tert-butylisopropyl)amino)lanthanum,tris(bis(dimethylsilyl)amino)lanthanum,tris((trimethylsilyl)(dimethylethylsilyl)amino)lanthanum,tris(bis(tert-butyl)amino)lanthanum, tris(bis(tert-amyl)amino)lanthanum,tris(tert-amyl-tert-butylamino)lanthanum,tris(tert-butyltrimethylsilylamino)lanthanum,tris(bis(dimethylethylsilyl)amino)lanthanum, and the like. Preferredorganometallic compounds include, for example, lanthanum amides.

In an embodiment of this invention, the organometallic compoundsinclude, for example, tris(bis(dimethylsilyl)amino)lanthanum,tris((trimethylsilyl)(dimethylethylsilyl)amino)lanthanum, andtris(bis(dimethylethylsilyl)amino)lanthanum.

In another embodiment of this invention, the organometallic compoundsinclude, for example, tris(bis(cyclohexyl)amino)lanthanum,tris(tert-butylisopropyl)amino)lanthanum,tris(bis(tert-butyl)amino)lanthanum, tris(bis(tert-amyl)amino)lanthanum,tris(tert-amyl-tert-butylamino)lanthanum, andtris(tert-butyltrimethylsilylamino)lanthanum.

Illustrative organometallic compounds of this invention can berepresented by the formulae:

The organometallic precursor compounds of this invention may behomoleptic, i.e., all R radicals are the same such astris(bis(tert-amyl)amino)lanthanum or heteroleptic, i.e., one or more ofthe R radicals are different from each other such astris(tert-butyltrimethylsilylamino)lanthanum.

As indicated above, this invention also relates to a process for theproduction of an organometallic compound comprising (i) reacting in afirst pot a nitrogen-containing compound with an alkali metal, or analkali metal-containing compound, or an alkaline earth metal, or analkaline earth metal-containing compound, in the presence of a solventand under reaction conditions sufficient to produce a first reactionmixture comprising a base material, (ii) adding said base material to asecond pot containing a metal source compound and optionally an aminecompound, (iii) reacting in said second pot said base material with saidmetal source compound and optionally said amine compound under reactionconditions sufficient to produce a second reaction mixture comprisingsaid organometallic compound, and (iv) separating said organometalliccompound from said second reaction mixture; wherein said organometalliccompound is represented by the formula M(NR₁R₂)_(x) wherein M is a metalor metalloid, R₁ is the same or different and is a hydrocarbon group ora heteroatom-containing group, R₂ is the same or different and is ahydrocarbon group or a heteroatom-containing group; R₁ and R₂ can becombined to form a substituted or unsubstituted, saturated orunsaturated cyclic group; R₁ or R₂ of one (NR₁R₂) group can be combinedwith R₁ or R₂ of another (NR₁R₂) group to form a substituted orunsubstituted, saturated or unsaturated cyclic group; x is equal to theoxidation state of M; and wherein said organometallic compound has (i) asteric bulk sufficient to maintain a monomeric structure and acoordination number equal to the oxidation state of M with respect toanionic ligands, and (ii) a molecular weight sufficient to possess avolatility suitable for vapor deposition. The organometallic compoundyield resulting from the process of this invention can be 60% orgreater, preferably 75% or greater, and more preferably 90% or greater.

In the processes described herein, the metal source compound, e.g., apure metal, a metal halide, a metal pseudohalide, and the like, startingmaterial may be selected from a wide variety of compounds known in theart. The invention herein most prefers metals selected from Sr, Ba, Sc,Y, Al, lanthanides, and the like. Illustrative metal source compoundsinclude, for example, La(CF₃SO₃)₃, LaCl₃, LaBr₃, LaI₃, SrCl₂, and thelike. Other illustrative metal source compounds include, for example,La(OiPr)₃, and the like. Preferred metal source compounds include, forexample, lanthanide halides and lanthanide trifluoromethanesulfonate.The metal source compound starting material can typically be anycompound or pure metal containing the central metal atom.

The processes of this invention for synthesizing organometalliccompounds with bulky amide ligands can also utilize triflate-based metalsource compounds. While most metalloamide compounds are reportedlysynthesized from the metal halides (e.g., LaCl₃), reaction rates withbulky amide compounds can be slow or non-detectable due to the largersteric profile of the ligands. Therefore, the triflate compounds, whichpossess better leaving groups, are more suited for this application.Furthermore, the resulting triflate ions are less likely to remain inthe coordination sphere (e.g., bridging) compared to halides (e.g., Cl),and therefore are better suited for producing neutral monomeric species.In addition, the increased solubility of the bulky amides, as well asthe triflates, may allow for the utilization of hydrocarbon solvents(e.g., toluene), which may be desirable in cases where coordination of aheteroatom containing solvent (e.g., tetrahydrofuran or ether) to thedesired compound is problematic.

The concentration of the metal source compound starting material canvary over a wide range, and need only be that minimum amount necessaryto react with the base material and optionally the amine compound and toprovide the given metal concentration desired to be employed and whichwill furnish the basis for at least the amount of metal necessary forthe organometallic compounds of this invention. In general, depending onthe size of the reaction mixture, metal source compound startingmaterial concentrations in the range of from about 1 millimole or lessto about 10,000 millimoles or greater, should be sufficient for mostprocesses.

In the processes described herein, the amine compounds may be selectedfrom a wide variety of compounds known in the art. Illustrative aminecompounds include, for example, diisopropylamine, di-tert-amylamine,tert-butylisopropylamine, di-tert-butylamine, dicyclohexylamine,tert-butyltrimethylsilylamine, diethyltetramethyldisilazane, and thelike. Preferred amine compound starting materials can be represented bythe formula NR₃R₄R₅ wherein each of R₃, R₄ and R₅ is the same ordifferent and is independently hydrogen, alkyl; a substituted orunsubstituted, saturated or unsaturated, hydrocarbon, aromatichydrocarbon, cycloaliphatic hydrocarbon, aromatic heterocycle, alkylhalide, silylated hydrocarbon, ether, polyether, thioether, ester,lactone, amide, amine, polyamine, nitrile; or mixtures thereof. Theamine compounds can include cyclic and chelating systems. The aminecompounds can also include the HCl salt of amines such as ammoniumchloride, dimethylammonium chloride, and the like. Preferably, each ofR₃, R₄ and R₅ is the same or different and is independently hydrogen,alkyl, or mixtures thereof. Preferred amine compounds include, forexample, di-tert-amylamine, tert-butylisopropylamine,di-tert-butylamine, tert-butyltrimethylsilylamine, anddiethyltetramethyldisilazane.

The concentration of the amine compound starting material can vary overa wide range, and need only be that minimum amount necessary to reactwith the base starting material and metal source compound. In general,depending on the size of the reaction mixture, amine compound startingmaterial concentrations in the range of from about 1 millimole or lessto about 10,000 millimoles or greater, should be sufficient for mostprocesses.

In the processes described herein, the base starting material may beselected from a wide variety of compounds known in the art. Illustrativebases include any base with a pKa greater than about 10, preferablygreater than about 20, and more preferably greater than about 25. Thebase material is preferably lithium diisopropylamide, lithiumdi-tert-amylamide, lithium tert-butylisopropylamide, lithiumdi-tert-butylamide, sodium di-tert-butylamide, lithiumdicyclohexylamide, lithium tert-butyltrimethylsilylamide, lithiumbis(ethyldimethylsilyl)amide, and the like. Lithium amides are preferredbase starting materials.

The concentration of the base starting material can vary over a widerange, and need only be that minimum amount necessary to react with theamine compound starting material and metal source compound. In general,depending on the size of the first reaction mixture, base startingmaterial concentrations in the range of from about 1 millimole or lessto about 10,000 millimoles or greater, should be sufficient for mostprocesses.

In one embodiment, the base starting material may be generated in situ,for example, lithiated amides, and the like. Generating the basestarting material in situ in the reaction vessel immediately prior toreaction with the metal source compound is beneficial from a puritystandpoint by eliminating the need to isolate and handle any reactivesolids. It is also less expensive.

With the in situ generated base starting material in place, addition ofthe metal source compound, e.g., La(CF₃SO₃)₃, can be performed throughliquid or solid addition, or in some cases more conveniently as asolvent solution or slurry. Although certain metal source compounds aremoisture sensitive and are used under an inert atmosphere such asnitrogen, it is generally to a much lower degree than the aminecompounds, for example, lithiated amides, amines and the like.Furthermore, many metal source compounds are denser and easier totransfer.

The base starting material can be prepared from the reaction of anitrogen-containing compound and an alkali metal, or an alkalimetal-containing compound, or an alkaline earth metal, or an alkalineearth metal-containing compound. The base starting material can beprepared by conventional processes known in the art.

The solvent employed in the processes of this invention may be anysaturated and unsaturated hydrocarbons, aromatic hydrocarbons, aromaticheterocycles, alkyl halides, silylated hydrocarbons, ethers, polyethers,thioethers, esters, thioesters, lactones, amides, amines, polyamines,nitriles, silicone oils, other aprotic solvents, or mixtures of one ormore of the above; more preferably, pentanes, heptanes, octanes,nonanes, decanes, xylene, tetramethylbenzene, dimethoxyethanes, diglyme,fluorinated hydrocarbons, and mixtures of one or more of the above; andmost preferably hexanes, ethers, THF, benzene, toluene, and mixtures ofone of more of the above. Any suitable solvent which does not undulyadversely interfere with the intended reaction can be employed. Mixturesof one or more different solvents may be employed if desired. The amountof solvent employed is not critical to the subject invention and needonly be that amount sufficient to solubilize the reaction components inthe reaction mixture. In general, the amount of solvent may range fromabout 5 percent by weight up to about 99 percent by weight or more basedon the total weight of the reaction mixture starting materials.

Reaction conditions for the processes for the reaction of the basematerial, the metal source compound, and optionally the amine compound,such as temperature, pressure and contact time, may also vary greatlyand any suitable combination of such conditions may be employed herein.The reaction temperature may be the reflux temperature of any of theaforementioned solvents, and more preferably between about −80° C. toabout 150° C., and most preferably between about 20° C. to about 80° C.Normally the reaction is carried out under ambient pressure and thecontact time may vary from a matter of seconds or minutes to a few hoursor greater. The reactants can be added to the reaction mixture orcombined in any order. The stir time employed can range from about 0.1to about 400 hours, preferably from about 1 to 75 hours, and morepreferably from about 4 to 16 hours, for all steps. In the embodiment ofthis invention which is carried out in a single pot, the base materialis not separated from the first reaction mixture prior to reacting withthe metal source compound and optionally the amine compound. In apreferred embodiment, the metal source compound is added to the firstreaction mixture at ambient temperature or at a temperature greater thanambient temperature.

The organometallic compounds prepared from the reaction of the basematerial, the metal source compound and optionally the amine compoundmay be selected from a wide variety of compounds. For purposes of thisinvention, organometallic compounds include compounds having ametal-nitrogen bond. Illustrative organometallic compounds include, forexample, metal amides, metal amines and the like.

The organometallic compounds of this invention can also be prepared by aone pot process. The one pot process is particularly well-suited forlarge scale production since it can be conducted using the sameequipment, some of the same reagents and process parameters that caneasily be adapted to manufacture a wide range of products. The processprovides for the synthesis of organometallic compounds using a processwhere all manipulations can be carried out in a single vessel, and whichroute to the organometallic compounds does not require the isolation ofan intermediate complex. A one pot process is described in U.S. patentapplication Ser. No. 10/678,074, filed Oct. 6, 2003, which isincorporated herein by reference.

For organometallic compounds prepared by the processes of thisinvention, purification can occur through recrystallization, morepreferably through extraction of reaction residue (e.g., hexane) andchromatography, and most preferably through sublimation anddistillation.

Those skilled in the art will recognize that numerous changes may bemade to the processes described in detail herein, without departing inscope or spirit from the present invention as more particularly definedin the claims below.

Examples of techniques that can be employed to characterize theorganometallic compounds formed by the synthetic methods described aboveinclude, but are not limited to, analytical gas chromatography, nuclearmagnetic resonance, thermogravimetric analysis, inductively coupledplasma mass spectrometry, differential scanning calorimetry, vaporpressure and viscosity measurements.

Relative vapor pressures, or relative volatility, of organometalliccompound precursors described above can be measured by thermogravimetricanalysis techniques known in the art. Equilibrium vapor pressures alsocan be measured, for example by evacuating all gases from a sealedvessel, after which vapors of the compounds are introduced to the vesseland the pressure is measured as known in the art.

The organometallic compound precursors described herein are preferablyliquid at room temperature, i.e., 20° C., and are well suited forpreparing in-situ powders and coatings. For instance, a liquidorganometallic compound precursor can be applied to a substrate and thenheated to a temperature sufficient to decompose the precursor, therebyforming a metal or metal oxide coating on the substrate. Applying aliquid precursor to the substrate can be by painting, spraying, dippingor by other techniques known in the art. Heating can be conducted in anoven, with a heat gun, by electrically heating the substrate, or byother means, as known in the art. A layered coating can be obtained byapplying an organometallic compound precursor, and heating anddecomposing it, thereby forming a first layer, followed by at least oneother coating with the same or different precursors, and heating.

Liquid organometallic compound precursors such as described above alsocan be atomized and sprayed onto a substrate. Atomization and sprayingmeans, such as nozzles, nebulizers and others, that can be employed areknown in the art.

In preferred embodiments of the invention, an organometallic compound,such as described above, is employed in gas phase deposition techniquesfor forming powders, films or coatings. The compound can be employed asa single source precursor or can be used together with one or more otherprecursors, for instance, with vapor generated by heating at least oneother organometallic compound or metal complex. More than oneorganometallic compound precursor, such as described above, also can beemployed in a given process.

As indicated above, this invention relates to organometallic precursormixtures comprising (a) an organometallic precursor compound representedby the formula M(NR₁R₂)_(x) wherein M is a metal or metalloid, R₁ is thesame or different and is a hydrocarbon group or a heteroatom-containinggroup, R₂ is the same or different and is a hydrocarbon group or aheteroatom-containing group; R₁ and R₂ can be combined to form asubstituted or unsubstituted, saturated or unsaturated cyclic group; R₁or R₂ of one (NR₁R₂) group can be combined with R₁ or R₂ of another(NR₁R₂) group to form a substituted or unsubstituted, saturated orunsaturated cyclic group; x is equal to the oxidation state of M; andwherein said organometallic compound has (i) a steric bulk sufficient tomaintain a monomeric structure and a coordination number equal to theoxidation state of M with respect to anionic ligands, and (ii) amolecular weight sufficient to possess a volatility suitable for vapordeposition; and (b) one or more different organometallic precursorcompounds (e.g., a hafnium-containing, aluminum-containing,strontium-containing, barium-containing, titanium-containingorganometallic precursor compound).

Deposition can be conducted in the presence of other gas phasecomponents. In an embodiment of the invention, film deposition isconducted in the presence of at least one non-reactive carrier gas.Examples of non-reactive gases include inert gases, e.g., nitrogen,argon, helium, as well as other gases that do not react with theorganometallic compound precursor under process conditions. In otherembodiments, film deposition is conducted in the presence of at leastone reactive gas. Some of the reactive gases that can be employedinclude but are not limited to hydrazine, oxygen, hydrogen, air,oxygen-enriched air, ozone (O₃), nitrous oxide (N₂O), water vapor,organic vapors, ammonia and others. As known in the art, the presence ofan oxidizing gas, such as, for example, air, oxygen, oxygen-enrichedair, O₃, N₂O or a vapor of an oxidizing organic compound, favors theformation of a metal oxide film.

As indicated above, this invention also relates in part to a method forproducing a film, coating or powder. The method includes the step ofdecomposing at least one organometallic compound precursor, therebyproducing the film, coating or powder, as further described below. Moreparticularly, this invention relates in part to a method for producing afilm, coating or powder by decomposing an organometallic precursorcompound represented by the formula M(NR₁R₂)_(x) wherein M is a metal ormetalloid, R₁ is the same or different and is a hydrocarbon group or aheteroatom-containing group, R₂ is the same or different and is ahydrocarbon group or a heteroatom-containing group; R₁ and R₂ can becombined to form a substituted or unsubstituted, saturated orunsaturated cyclic group; R₁ or R₂ of one (NR₁R₂) group can be combinedwith R₁ or R₂ of another (NR₁R₂) group to form a substituted orunsubstituted, saturated or unsaturated cyclic group; x is equal to theoxidation state of M; and wherein said organometallic compound has (i) asteric bulk sufficient to maintain a monomeric structure and acoordination number equal to the oxidation state of M with respect toanionic ligands, and (ii) a molecular weight sufficient to possess avolatility suitable for vapor deposition; thereby producing the film,coating or powder. Typically, the decomposing of said organometallicprecursor compound is thermal, chemical, photochemical orplasma-activated.

Deposition methods described herein can be conducted to form a film,powder or coating that includes a single metal or a film, powder orcoating that includes a single metal oxide. Mixed films, powders orcoatings also can be deposited, for instance mixed metal oxide films. Amixed metal oxide film can be formed, for example, by employing severalorganometallic precursors, at least one of which being selected from theorganometallic compounds described above.

Gas phase film deposition can be conducted to form film layers of adesired thickness, for example, in the range of from about 1 nm to over1 mm. The precursors described herein are particularly useful forproducing thin films, e.g., films having a thickness in the range offrom about 10 nm to about 100 nm. Films of this invention, for instance,can be considered for fabricating metal electrodes, in particular asn-channel metal electrodes in logic, as capacitor electrodes for DRAMapplications, and as dielectric materials.

The method also is suited for preparing layered films, wherein at leasttwo of the layers differ in phase or composition. Examples of layeredfilm include metal-insulator-semiconductor, and metal-insulator-metal.

In an embodiment, the invention is directed to a method that includesthe step of decomposing vapor of an organometallic compound precursordescribed above, thermally, chemically, photochemically or by plasmaactivation, thereby forming a film on a substrate. For instance, vaporgenerated by the compound is contacted with a substrate having atemperature sufficient to cause the organometallic compound to decomposeand form a film on the substrate.

The organometallic compound precursors can be employed in chemical vapordeposition or, more specifically, in metalorganic chemical vapordeposition processes known in the art. For instance, the organometalliccompound precursors described above can be used in atmospheric, as wellas in low pressure, chemical vapor deposition processes. The compoundscan be employed in hot wall chemical vapor deposition, a method in whichthe entire reaction chamber is heated, as well as in cold or warm walltype chemical vapor deposition, a technique in which only the substrateis being heated.

The organometallic compound precursors described above also can be usedin plasma or photo-assisted chemical vapor deposition processes, inwhich the energy from a plasma or electromagnetic energy, respectively,is used to activate the chemical vapor deposition precursor. Thecompounds also can be employed in ion-beam, electron-beam assistedchemical vapor deposition processes in which, respectively, an ion beamor electron beam is directed to the substrate to supply energy fordecomposing a chemical vapor deposition precursor. Laser-assistedchemical vapor deposition processes, in which laser light is directed tothe substrate to affect photolytic reactions of the chemical vapordeposition precursor, also can be used.

The method of the invention can be conducted in various chemical vapordeposition reactors, such as, for instance, hot or cold-wall reactors,plasma-assisted, beam-assisted or laser-assisted reactors, as known inthe art.

Examples of substrates that can be coated employing the method of theinvention include solid substrates such as metal substrates, e.g., Al,Ni, Ti, Co, Pt, Ta; metal aluminates; metal silicides, e.g., TiSi₂,CoSi₂, NiSi₂; semiconductor materials, e.g., Si, SiGe, GaAs, InP,diamond, GaN, SiC; insulators, e.g., SiO₂, Si₃N₄, HfO₂, Ta₂O₅, Al₂O₃,barium strontium titanate (BST); barrier materials, e.g., TiN, TaN; oron substrates that include combinations of materials. In addition, filmsor coatings can be formed on glass, ceramics, plastics, thermosetpolymeric materials, and on other coatings or film layers. In preferredembodiments, film deposition is on a substrate used in the manufactureor processing of electronic components. In other embodiments, asubstrate is employed to support a low resistivity conductor depositthat is stable in the presence of an oxidizer at high temperature or anoptically transmitting film.

The method of this invention can be conducted to deposit a film on asubstrate that has a smooth, flat surface. In an embodiment, the methodis conducted to deposit a film on a substrate used in wafermanufacturing or processing. For instance, the method can be conductedto deposit a film on patterned substrates that include features such astrenches, holes or vias. Furthermore, the method of the invention alsocan be integrated with other steps in wafer manufacturing or processing,e.g., masking, etching and others.

Chemical vapor deposition films can be deposited to a desired thickness.For example, films formed can be less than 1 micron thick, preferablyless than 500 nanometer and more preferably less than 200 nanometersthick. Films that are less than 50 nanometer thick, for instance, filmsthat have a thickness between about 1 and about 20 nanometers, also canbe produced.

Organometallic compound precursors described above also can be employedin the method of the invention to form films by atomic layer deposition(ALD) or atomic layer nucleation (ALN) techniques, during which asubstrate is exposed to alternate pulses of precursor, oxidizer andinert gas streams. Sequential layer deposition techniques are described,for example, in U.S. Pat. No. 6,287,965 and in U.S. Pat. No. 6,342,277.The disclosures of both patents are incorporated herein by reference intheir entirety.

For example, in one ALD cycle, a substrate is exposed, in step-wisemanner, to: a) an inert gas; b) inert gas carrying precursor vapor; c)inert gas; and d) oxidizer, alone or together with inert gas. Ingeneral, each step can be as short as the equipment will permit (e.g.milliseconds) and as long as the process requires (e.g. several secondsor minutes). The duration of one cycle can be as short as millisecondsand as long as minutes. The cycle is repeated over a period that canrange from a few minutes to hours. Film produced can be a few nanometersthin or thicker, e.g., 1 millimeter (mm).

The method of the invention also can be conducted using supercriticalfluids. Examples of film deposition methods that use supercritical fluidthat are currently known in the art include chemical fluid deposition;supercritical fluid transport-chemical deposition; supercritical fluidchemical deposition; and supercritical immersion deposition.

Chemical fluid deposition processes, for example, are well suited forproducing high purity films and for covering complex surfaces andfilling of high-aspect-ratio features. Chemical fluid deposition isdescribed, for instance, in U.S. Pat. No. 5,789,027. The use ofsupercritical fluids to form films also is described in U.S. Pat. No.6,541,278 B2. The disclosures of these two patents are incorporatedherein by reference in their entirety.

In an embodiment of the invention, a heated patterned substrate isexposed to one or more organometallic compound precursors, in thepresence of a solvent, such as a near critical or supercritical fluid,e.g., near critical or supercritical CO₂. In the case of CO₂, thesolvent fluid is provided at a pressure above about 1000 psig and atemperature of at least about 30° C.

The precursor is decomposed to form a metal film on the substrate. Thereaction also generates organic material from the precursor. The organicmaterial is solubilized by the solvent fluid and easily removed awayfrom the substrate. Metal oxide films also can be formed, for example byusing an oxidizing gas.

In an example, the deposition process is conducted in a reaction chamberthat houses one or more substrates. The substrates are heated to thedesired temperature by heating the entire chamber, for instance, bymeans of a furnace. Vapor of the organometallic compound can beproduced, for example, by applying a vacuum to the chamber. For lowboiling compounds, the chamber can be hot enough to cause vaporizationof the compound. As the vapor contacts the heated substrate surface, itdecomposes and forms a metal or metal oxide film. As described above, anorganometallic compound precursor can be used alone or in combinationwith one or more components, such as, for example, other organometallicprecursors, inert carrier gases or reactive gases.

In a system that can be used in producing films by the method of theinvention, raw materials can be directed to a gas-blending manifold toproduce process gas that is supplied to a deposition reactor, where filmgrowth is conducted. Raw materials include, but are not limited to,carrier gases, reactive gases, purge gases, precursor, etch/clean gases,and others. Precise control of the process gas composition isaccomplished using mass-flow controllers, valves, pressure transducers,and other means, as known in the art. An exhaust manifold can convey gasexiting the deposition reactor, as well as a bypass stream, to a vacuumpump. An abatement system, downstream of the vacuum pump, can be used toremove any hazardous materials from the exhaust gas. The depositionsystem can be equipped with in-situ analysis system, including aresidual gas analyzer, which permits measurement of the process gascomposition. A control and data acquisition system can monitor thevarious process parameters (e.g., temperature, pressure, flow rate,etc.).

The organometallic compound precursors described above can be employedto produce films that include a single metal or a film that includes asingle metal oxide. Mixed films also can be deposited, for instancemixed metal oxide films. Such films are produced, for example, byemploying several organometallic precursors. Metal films also can beformed, for example, by using no carrier gas, vapor or other sources ofoxygen.

Films formed by the methods described herein can be characterized bytechniques known in the art, for instance, by X-ray diffraction, Augerspectroscopy, X-ray photoelectron emission spectroscopy, atomic forcemicroscopy, scanning electron microscopy, and other techniques known inthe art. Resistivity and thermal stability of the films also can bemeasured, by methods known in the art.

Atomic layer deposition and chemical vapor deposition of silicates andaluminates can be useful for many next generation materials (e.g.,lanthanum aluminates for dielectrics).

Various modifications and variations of this invention will be obviousto a worker skilled in the art and it is to be understood that suchmodifications and variations are to be included within the purview ofthis application and the spirit and scope of the claims.

1. A process for the production of an organometallic compound comprising(i) reacting in a first pot a nitrogen-containing compound with analkali metal, or an alkali metal-containing compound, or an alkalineearth metal, or an alkaline earth metal-containing compound, in thepresence of a solvent and under reaction conditions sufficient toproduce a first reaction mixture comprising a base material, (ii) addingsaid base material to a second pot containing a metal source compoundand optionally an amine compound, (iii) reacting in said second pot saidbase material with said metal source compound and optionally said aminecompound under reaction conditions sufficient to produce a secondreaction mixture comprising said organometallic compound, and (iv)separating said organometallic compound from said second reactionmixture; wherein said organometallic compound is represented by theformula M(NR₁R₂)_(x) wherein M is a metal or metalloid, R₁ is the sameor different and is a hydrocarbon group or a heteroatom-containinggroup, R₂ is the same or different and is a hydrocarbon group or aheteroatom-containing group; R₁ and R₂ can be combined to form asubstituted or unsubstituted, saturated or unsaturated cyclic group; R₁or R₂ of one (NR₁R₂) group can be combined with R₁ or R₂ of another(NR₁R₂) group to form a substituted or unsubstituted, saturated orunsaturated cyclic group; x is equal to the oxidation state of M; andwherein said organometallic compound has (i) a steric bulk sufficient tomaintain a monomeric structure and a coordination number equal to theoxidation state of M with respect to anionic ligands, and (ii) amolecular weight sufficient to possess a volatility suitable for vapordeposition.
 2. The process of claim 1 wherein the metal source compoundcomprises a pure metal, a metal halide, or a metal pseudohalide.
 3. Theprocess of claim 1 wherein the metal source compound comprisesLa(CF₃SO₃)₃, LaCl₃, LaBr₃, LaI₃, or SrCl₂.
 4. The process of claim 1wherein the metal source compound comprises a lanthanide halide or alanthanide trifluoromethanesulfonate.
 5. The process of claim 1 whereinthe base material comprises lithium diisopropylamide, lithiumdi-tert-amylamide, lithium tert-butylisopropylamide, lithiumdi-tert-butylamide, sodium di-tert-butylamide, lithiumdicyclohexylamide, lithium tert-butyltrimethylsilylamide, or lithiumbis(ethyldimethylsilyl)amide.
 6. The process of claim 1 wherein the basematerial has a pKa greater than about
 10. 7. The process of claim 1wherein the amine compound comprises diisopropylamine,di-tert-amylamine, tert-butylisopropylamine, di-tert-butylamine,dicyclohexylamine, tert-butyltrimethylsilylamine, ordiethyltetramethyldisilazane.
 8. The process of claim 1 wherein theorganometallic compound yield is 60% or greater.
 9. A method forproducing a film, coating or powder by decomposing an organometallicprecursor compound represented by the formula M(NR₁R₂)_(x) wherein M isa metal or metalloid, R₁ is the same or different and is a hydrocarbongroup or a heteroatom-containing group, R₂ is the same or different andis a hydrocarbon group or a heteroatom-containing group; R₁ and R₂ canbe combined to form a substituted or unsubstituted, saturated orunsaturated cyclic group; R₁ or R₂ of one (NR₁R₂) group can be combinedwith R₁ or R₂ of another (NR₁R₂) group to form a substituted orunsubstituted, saturated or unsaturated cyclic group; x is equal to theoxidation state of M; and wherein said organometallic compound has (i) asteric bulk sufficient to maintain a monomeric structure and acoordination number equal to the oxidation state of M with respect toanionic ligands, and (ii) a molecular weight sufficient to possess avolatility suitable for vapor deposition; thereby producing the film,coating or powder.
 10. The method of claim 9 wherein the decomposing ofsaid organometallic precursor compound is thermal, chemical,photochemical or plasma-activated.
 11. The method of claim 9 whereinsaid organometallic precursor compound is vaporized and the vapor isdirected into a deposition reactor housing a substrate.
 12. The methodof claim 11 wherein said substrate is comprised of a material selectedfrom the group consisting of a metal, a metal silicide, a metalaluminate, a semiconductor, an insulator and a barrier material.
 13. Themethod of claim 11 wherein said substrate is a patterned wafer.
 14. Themethod of claim 9 wherein said film, coating or powder is produced by agas phase deposition.
 15. The method of claim 9 wherein said film,coating or powder is produced by a chemical vapor deposition or atomiclayer deposition.